Characterization of UV–Vis–NIR optical constants of encapsulant for accurate determination of absorption and backscattering losses in photovoltaics modules

The determination of the optical properties of encapsulant for photovoltaic modules is essential for cell-to-module (CTM) performance analysis, UV-durability studies and as input parameters of modelling tools. Some innovative polymer encapsulants used in heterojunction module manufacturing, such as polyolefin elastomer or thermoplastic polyolefin, show a non-negligible optical scattering behaviour in addition to refraction and absorption mechanisms, making challenging the extraction of optical properties in general, and optical indices in particular.